The present invention relates to a process for preparing an extract containing at least one hydroperoxide. More specifically, the present invention relates to a process for preparing an extract containing at least one hydroperoxide, in which extract said hydroperoxide is prevented from decomposing undesirably.
As a process for producing an object compound such as resorcinol using, as a starting material, an aromatic hydrocarbon substituted with an alkyl group such as 1,3-diisopropylbenzene, there is known a process comprising the steps of (i) to (v) as mentioned below:
(i) subjecting a liquid material containing an aromatic hydrocarbon substituted with an alkyl group to oxidation, thereby obtaining a liquid reaction mixture,
(ii) extracting hydroperoxides in the liquid reaction mixture with an aqueous alkali solution, thereby obtaining an extract-1,
(iii) extracting the hydroperoxides in the extract-1 with an organic solvent, thereby obtaining an extract-2, wherein the aqueous alkali solution separated in this step is recycled to the above-mentioned step (ii) or step (iii),
(iv) subjecting the hydroperoxides in the extract-2 to acid decomposition, thereby obtaining a reaction mixture containing the object compound and a by-produced acetone, and
(v) distilling the reaction mixture to separate the object compound and a low boiling point fraction such as the organic solvent used, wherein the organic solvent separated in this step is recycled to the above-mentioned step (iii).
However, the above-mentioned process comprising the recycling system has a problem that the desired hydroperoxides in the extract-1 are apt to decompose therein undesirably, when a concentration of acetone in the extract-1 obtained in the step (ii) is high, or when an A value of the aqueous alkaline solution used in the step (ii) is high, which A value is as defined below.
An object of the present invention is to provide a process for preparing an extract containing at least one hydroperoxide, according to which the hyroperoxide(s) in the extract-1 is(are) prevented from decomposing undesirably.
That is, the present invention provides a process for preparing an extract containing at least one hydroperoxide, which comprises the steps of:
(1) oxidizing an aromatic hydrocarbon substituted with an alkyl group to obtain a liquid reaction mixture, and
(2) extracting at least one hydroperoxide with an aqueous alkali solution to obtain an extract having a concentration of acetone of not more than 1% by weight.
The present invention also provides a process for preparing an extract containing at least one hydroperoxide, which comprises the steps of,
(1) oxidizing an aromatic hydrocarbon substituted with an alkyl group to obtain a liquid reaction mixture, and
(2) extracting at least one hydroperoxide with an aqueous alkali solution having an A value of not more than 10 to obtain an extract, wherein the A value is a volume in terms of ml of the below-defined aqueous hydrochloric acid solution consumed between a first inflection point and a second inflection point in a pH titration curve obtained when 10 ml of the aqueous alkali solution is subjected to titration with a 1 N(normal) aqueous hydrochloric acid solution, provided that when the inflection point is not clear, or when there are three or more inflection points, the A value is a volume in terms of ml of said aqueous hydrochloric acid solution consumed during a pH transition of from 7 to 2 in the above-defined titration.